MK Sentry Single Pole RCBOs RCBOs are a mixture of a Type B MCB & a 30m A RCD, this allows over current & earth protection in one product, & this ensures that if there is a fault the circuit is broken & supply stopped. MK Sentry RCBOs are fitted with a dolly which can be locked off without compromising the tripping capabilities of the RCBO Dimensions 112 x 18 x 73mm Capable of taking 25mm 2 Live, & 16mm 2 Neutral